Re: foreach statment?
От | Stephan Szabo |
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Тема | Re: foreach statment? |
Дата | |
Msg-id | 20030519162038.S43727-100000@megazone23.bigpanda.com обсуждение исходный текст |
Ответ на | foreach statment? (Abdul-wahid Paterson <aw@lintrix.net>) |
Список | pgsql-general |
On 19 May 2003, Abdul-wahid Paterson wrote: > Hi, > > I have a situation (that I seem to come across often - hence the > question) where I have 3 tables. > > items > items_options > options > > items has a many-to-many relationship with options so items_options is > merely a link table with an item_id and and option_id. > > What I need to do is give a default option to all items that don't have > any options. > > I would do something like this: > > select i.item_id from items i where (select count(item_id) from > items_options where item_id=i.item_id) = 0; > > And then write a script that will go through the outputted list of > item_id's and for each one do an insert statement like: > > insert into items_options values ($item_id, $n); Maybe something like (not really tested) insert into items_options select item_id, $n from items i where not exists (select item_id from item_options where i.item_id=item_id);
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